The most dangerous disease of rhododendrons is phytophthorosis. Light brown spots that darken quickly develop on the infected roots.Infected plants stop growing. Their leaves turn light green or greyish, then curl down the main vein and remain on the plant.In case of first symptoms, immediately apply Ridomil Gold MZ Peptide 67.8 WG.
Browning of the edges and tops of leaves is most often the result of unfavorable weather conditions (temperature fluctuations can be prevented by using agrotextile for the cover of the shrubs). Then the damaged tissue is inhabited by fungi.Then it is worth using fungicides, e.g. Topsin M 500 SC or Polyram 70 WG. When the leaves develop spots of different sizes and colors, it is a sign of fungus infestation.Infected bushes grow more slowly and are no longer ornamental.
Use Topsin M 500 SC in this case. The same remedy is effective when symptoms of powdery mildew (white powdery coating) or gray mold appear on the leaves. Score 250 EC should also be used alternatively. In the event of gray mold symptoms, treatment should be performed with Switch 62.5 WG or Rovral Aquaflo 500 S.C.
The pest that attacks rhododendrons is also the marshmallow.The larvae of this beetle feed on the underground organs of the plant, damaging the root collar and roots.Infested bushes wilt and die. In spring, adult insects bite out sinus holes at the edges of the leaves. Insects feed at night, so we carry out the chemical treatment late in the evening and repeat it after a week.For this purpose, you can use, for example, Karate Zeon 050 CS.
Apart from the swollen bud, there are also azalea aphid colonies on the shoots and buds. They forage in colonies on the lower side of the apical shoots and on flower buds. Dthey form leaves and destroy flower buds.After noticing the first aphids, the plants should be sprayed with Karate Zeon 050 SC or Sumi-Alpha 050 EC.
